Other studies compare the same measure under two or more different conditions.

"My second study compared Miami students to other schools and found little difference," he said.

Not a single medical study has looked at the program or compared it to other popular diets.

The study, to be completed early next year, compared two groups of overweight people.

A second study compares the birth records of 48 children with cancer to 480 without.

There are no studies comparing the open versus closed system design.

But no study directly comparing the drugs' effectiveness has been done.

Several studies are now comparing this alternative to aspirin alone.

The 1990 study, which the agency published in early 1991, compared the safety records of vehicles built before and after the standard.

The most obvious example were studies comparing a new drug to a placebo.